fernstrum



Feb. 14, 1956 R. W. FERNSTRUM DUAL IMPELLER PUMP 2 Sheets-Sheet l Filed OCT.. 6, 1952 Feb. M, E96 R. W. FERNSTRUM DUAL IMPELLER PUMP 2 Sheets-Sheet 2 INVENTOR 7257/710] /iwzmfd Filed Oc.. 6, 1952 United States Patent O DUAL IMPELLER PUMP Robert W. Fernstrum, Menominee, Mich., assigner to Marine Products Company, Detroit, Mich., a corporation of Michigan Application October 6, 1952, Serial No. 313,367 4 Claims. (Cl. 10S-4) This invention relates to hydraulic pumps and, in particular, to duplex pumps.

One object of this invention is to provide a dual rotor pump having a centrifugal pump unit and a resilient rotor pump unit arranged to draw suction from the centrifugal pump chamber so as to keep the centrifugal pump constantly primed, regardless of its frequentloss of suction due to the decline in water to be pumped by the centrifugal pump.

Another object is to provide a dual rotor pump of the foregoing character wherein the centrifugal pump performs intermittent demand service, such as in 'marine installations for bilge pump duty, and the resilient rotor pump performs constant, demand service, such as for exhaust cooling pump duty.

Another object is to provide a dual rotor pump of the foregoing characterywherein a portion of the discharge from the resilient rotor pump is diverted into the centrifugal pump chamber, preferably near the top thereof, so as to keep it constantly primed, the balance of the discharge being directed to the location to which it is supplied for performing its additional service, such as exhaust cooling service in a marine installation.

Another object is to provide a centrifugal pump having a rotor shaft mounted on a ,bearing disposed in the suction chamber of the pump sothat the action of the pump will tend to draw sand or other foreign matter out of the rotor shaft bearing rather than force it into the bearing, as in prior centrifugal pumps, so that the present invention reduces bearing wear and consequently increases the working life of a pump and decreases the frequency of repairs. j

Other objects and advantages of the invention will become apparent during the course of the following descrip# tion of the accompanying drawing, wherein: V

Figure l is a central longitudinal section through a dual rotor pump, according to one form of the invention;

Figure 2 is a vertical cross-Section throughthe centrifugal pump unit of the dual rotor pump taken along the line 2 2 in Figure 1;

Figure 3 is a vertical cross-section through the resilient rotor pump unit of the dual rotor pump of Figure l, taken along the line 3 3 in Figure 1;

Figure 4 is a horizontal section through the resilient rotor pump unit taken along the line 4 4 in Figure 3; and

Figure 5 is a side elevation, on a reduced scale, of the drive pulley for the pump, removed from the pump.

Hitherto, centrifugal pumps have been unsatisfactory for intermittent demand service, such as for bilge pump service in marine installations, because of the loss of suction occurring when the bilge water level falls to the level of the pump intake and thereby admits air. Selfpriming centrifugal pumps have been devised in the attempt to overcome this difficulty, but have proved to be inferior in ethciency. Furthermore, conventional centrifugal pumps have hitherto had rotors mounted on shafts rotatably supported by shaft bearings located on the pressure side of the pump, so that sand drawn into the pump was forced into the bearing, causing increased wear and frequency of repair.

The present invention provides a dual rotor pump wherein a rotary pump rotor, preferably of resilient construction, is mounted on the same shaft as the centrifugal pump rotor, but in a different pump chamber, a portion of the discharge of the rotary pump being diverted into the centrifugal pump chamber to maintain it in a constantly primed state regardless of the intermittent nature of its service and the loss of suction by drawing in air through its suction port when the level of the liquid which it is pumping falls below the suction port level. The present invention alsoV directs the remainder of the discharge of the rotary pump to a location where it performs other constant demand service, such as exhaust cooling service in marine installations. The centrifugal pump rotor shaft bearing of the dual rotor pump of the present invention is also placed in the suction chamber or on the suction side of the pump where the suction exerted by the rotor tends to draw sand or other foreign matter out of the pump bearing and hence increases the working life and decreases the frequency of repairs.

Referring to the drawings in detail, Figure l shows a dual rotor pump, generally designated 16, according to one form of the invention as including a centrifugal pump unit and a resilient rotor pump unit, generally designated 11 and 12 respectively having housings 13 and 14 respectively which are joined to one another to form' a housing assembly, generally designated 15.

The centrifugal pump housing 13 is provided with a central rotor chamber 16 opening into a peripheral discharge passageway or volute 17 arranged tangentially to the chamber `16 and separated therefrom by a tonguelike partition wall 18 and terminating in a threaded outlet or discharge port 19 located within a tubular discharge port boss 20 (Figure 2). The centrifugal pump housing 13 is also provided with an intake or suction chamber 21 (Figure l) connected at one end to a threaded intake or suction port 22 located in a Vboss 23 and at its other end is Vseparated from the centrifugal rotor chamber 16 by an approximately annular partition wall 24 having a central approximately circular opening 25 interconnecting the chambers 16 and 21.

Projecting inwardly into the intake chamber 21 from one end wall 26 of the centrifugal pump housing 13 is a bearing hangerL or bracket 27 (Figure 1) having a tubular bearing holder 2S with a bore 29 containing a bearing member 30, such as a bronze bushing, havinga bearing bore 31 extending therethrough. The bracket 27 and its bearing holder 28 serve as an internal partition wall to set off a seal chamber 32 from the centrifugal pump intake or suction chamber 21 but having the same end wall 26 as the intake chamber 21. The end wall V26 is provided with a circular opening or bore 33 into which the annular ange 34 of a combined end plate and bearing support 35 is inserted. The end plate 35 is provided with a disc-shaped portion 36 carrying the flange34 and secured in abutting relationship to the partition wall26 by bolts or cap screws 37.

Projecting outwardly from the disc portion of the combined end plate and bearing support 35 is a tubular boss or extension 38 having an annular bearing seat 39 terminating at its inner end in an annular bearing-retaining ridge or shoulder 4t) and having near its outer end an internal annular groove 41 adapted to receive a retaining ring or snap ring 42 for holding therein an anti-friction bearing unit, generally designated 43. The latter is conventional and consists of the usual outer race 44 mounted in the annular bearing seat 39, an annular row of spaced bearing balls 45 and an inner race 46 rotatably supported by the bearing balls 45, the inner and outer races being annularly grooved to receive the balls between them. The ring 42 holds the outer race 44 of the anti-friction bearing unit 43 in position against the annular shoulder or ridge 40.

Rotatably mounted in the bearing bore 31 of the bearing 30 (Figure l) is a pump rotor shaft 50 having near its outer end a reduced diameter portion 51 engaging and holding the inner race 46 of the anti-friction bearing unit 43. Between the axially-spaced bearings 30 and 43 the shaft 50 passes through a sleeve or collar 52 having a flange 53 which engages a resilient gasket 54 mounted within the bore 55 inside the ilange 34 on the combined end plate and bearing holder 35. The collar 52 is slidably mounted on the shaft 50 so as to push the gasket 54 against the disc-shaped portion 36 and is caused to do so by the action of a flexible shaft sealing device, generally designated 56. The latter is conventional and consists of a pair of axiallyspaced flanged collars 57 and 58 carrying a correspondingly flanged resilient tubular member 59 of elastic deformable material, such as rubber or synthetic rubber and held in place by a pair of angle rings 60 and 61 placed outside the tubular member 59 and urged in opposite directions away from one another by a helical spring 62. The collar 58 carries an angle ring 63 which cooperates with the angle ring 61 to hold the inner flanged end of the resilient member 59 firmly in position, and is in turn held in place by an annular washer 64 retained in position by a snap ring 65 inserted in an annular groove 66 in the pump rotor shaft 50. Mounted on the shaft 50 between the collar 52 and the antifriction bearing unit 43 is a resilient ring 67. In order to support the pump casing assembly 15, the centrifugal pump housing 13 is provided with a base 68 spaced away from the remainder of the casing 13 by 'l webs 69 and connected at its inner end to the portion 70 of the casing 13 containing the volute 17.

In order to rotate the shaft 50, the latter at its outer end is provided with a further reduced diameter portion 71 containing a keyway 72 and also having a threaded portion 73 carrying a nut 74 and washers 75. Mounted on the reduced diameter portion 71 and held in place by the nut 74 and washer 75 is the hub 76 of a drive pulley, generally designated 77, the hub 76 of which is provided with a keyway 78 carrying a key 79 which drivingly engages the shaft portion 71. The hub 76 of the pulley 77 also engages the inner bearing race 46 and holds it in position upon the reduced diameter shaft portion 51.

The pulley 77 is provided with a cylindrical or drum portion 80 terminating at one end in a flared portion or conical flange 81 forming one wall of a V-belt groove 82, the other wall of which is formed by the oppositelyflared portion or conical flange 83 extending outwardly from a sleeve 84 which is telescopingly mounted upon the drum portion 80 so as to slidingly engage the latter. The sleeve 84 and its flange 83 in assembly form a movable or adjustable pulley half 85 and the sleeve 84 is provided with a multiplicity of oblique slots 86. Each of the slots 86 extends in an oblique direction for a short distance around the sleeve 34, which is adjustably and releasably locked in position by clamping screws S7 threaded through the slots 86 into threaded holes 88 in the pulley drum portion 80.

The volute housing portion 70 is provided with a boss 90 containing a threaded bore 91 which receives a screw plug 92 for drainage purposes. The shaft 50 at its inner end is provided with a reduced diameter portion 93 which is provided with a keyway 94 and carries a hub 95 of a centrifugal pump rotor, generally designated 96 drivingly connected to the shaft portion 93 by a key 97 mounted in a keyway 93 within the hub 95. The centrifugal pump rotor 96 is mounted within the chamber 16 and is provided with a disc-like vane supporting portion 99 carrying the lateral edges of arcuate or spiral vanes 100, the inner ends of which are secured to the hub 95 and radiate outwardly therefrom (Figures l and 2). The outer edges 101 of the vanes 100 are inclined, to correspond to the correspondinglyinclined or conical inner surface 102 of the partition wall 24. The outer ends 103 of the vanes 100 terminate at the annular opening 104 between the rotor chamber 16 and the volute chamber or passageway 17 (Figure l). Adjacent the chamber 16, the centrifugal pump housing 13 is provided with a rear wall 105 containing a central opening 106 leading into the rotor chamber 16.

Secured within the opening 106 in the centrifugal pump casing end wall is the inner end wall 107 of the resilient rotor pump housing 14, the latter being held in place by studs 10S threaded into the centrifugal pump housing end wall 105 and carrying nuts 108t1 threaded thereon. The end wall 107 in turn is provided with a central opening or bore 109 which receives the hub 110 of a resilient rotor 111 which is also bored at 112 to receive the reduced diameter shaft portion 93 and provided with a keyway 113 similar to the keyway 98 by which it is drivingly connected to the shaft 50 by the key 97 in the keyway 94. The inner end of the shaft 50 is threaded as at 114 to receive a retaining nut 115 by which the hubs 95 and 11) of the rotors 96 and 111 are held in position, so that they rotate in unison but in different pump chambers 16 and 116 respectively.

The chamber 116 is of approximately cylindrical shape and has a cylindrical bore 117 in which is inserted the corresponding cylindrical portion 118 of an end plate 119 having a flange 120 engaging the housing 14 and held in position thereagainst by the studs 108 and nuts 108e. The end plate 119 on its lower side is provided with a boss 121 containing a drain port 122 threaded as at 123 to receive a threaded drain plug 124. In its upper portion the end plate 119 is provided with a bore 125 and a counterbore 126 for receiving a bolt 127 and sealing ring 128 respectively. The head 129 of the bolt 127 is seated in a countersink 130 within a cam plate 131 (Figures 1 and 4) which has an inclined ramp 132 or cam surface on the inner side thereof. The outer side of the cam plate 131, which is of arcuate shape, is held against the inner surface 133 of the end plate 119 by a nut 134 threaded upon the bolt 127.

The rotor chamber 116 opens into intake or suction and outlet or discharge chambers 135 and 136 respectively (Figure 3) separated from one another by a partition wall 137 terminating at its lower end in an arcuate portion 138. The chambers 135 and 136 are formed within a housing extension 139 of the pump housing 14 and are provided with bosses 140 and 141 containing threaded intake and discharge ports 142 and 143 respectively. In order to constantly prime the centrifugal pump chamber 16 by supplying it constantly with water or other liquid, the pump housings 13 and 14 are provided with aligned passageways 144 and 145 respectively leading from the outlet or discharge chamber 136 of the pump housing 14 (Figures 1 and 3) to the upper part of the centrifugal pump chamber 16 immediately beneath the tongue or partition wall 18.

The hub 110 of the rotor 111 is provided with au outwardly-extending disc-like flange (Figure l) containing circumferentially-spaced apertures 151. Secured to the ange portion 150 and hub 110 and extending through the holes 151 is a resilient rotor element, generally designated 152, in the form of a disc portion 153 extending over and bonded to the hub 110 and its flange 150. The resilient rotor element 152 is provided with an annular hub portion 154 and is also provided with radial vanes 155 (Figures 3 and 4) integral with the disc portion 153 and extending in directions inclined to the axis of rotation in a longitudinal direction and disposed radially thereto in a transverse direction. The vanes 155 during manufacture are molded integral with :tyre-1,457.`

the hub-154 and disc portion 153, but are later severed at their inner ends from the hub portion 154 so as to be capable of flexing relatively thereto. The vanes 155 move in an annular path wherein they engage the inner wall 133 of the end plate 119 and the ramp 132 of the cam plate 131 disposed on opposite sides of the partition 137 (Figures 3 and 4) separating the intake or suction chamber 135 from the outlet or discharge chamber 136.

Operation In the operation of the dual rotor pump 10, power is applied to the pulley 77 by means of a belt in the pulley groove S2, simultaneously rotating the centrifugal pump rotor 96 within its rotor chamber 16 and likewise rotating the resilient rotor 111 within the resilient rotor chamber 116. As the resilient rotor 111 rotates in a counterclockwise direction (Figure 3), its vanes draw in water or other liquid through the intake or suction port 142 into the intake or suction chamber 135 and thence into the pump chamber 116, discharging the liquid into the outlet or discharge chamber 136 and port 143 as the resilient vanes 155 flex while they pass over the ramp 132 of the cam plate 131. As the vanes are compressed or pushed inward on the right-hand side of the cam plate 131 as they climb the ramp 132 (Figure 4), they expel the water by the compression thus created, whereas while the vanes 155 descend the ramp 132 on the left-hand side of the cam plate 13 1 on the opposite side of the partition 137, they expand and thereby create a suction action or effect which draws in liquid through the intake or suction port 142 and chamber 135.

Meanwhile, however, a portion of the liquid discharged in this manner into the outlet or discharge chamber 136 passes through the aligned passageways 145 and 144 into the upper portion of the centrifugal pump chamber 6 (Figure l) maintaining this chamber in a constantly primed condition regardless of the presence or absence of liquid entering the centrifugal pump intake chamber 21 through the intake or suction port 22.

While this is occurring, the centrifugal pump rotor 96 is rotating in a counterclockwise direction, expelling water or other liquid by centrifugal action off the ends 103 of its vanes 160 into the volute passageway 17 and thereby drawing in liquid through the eye or central opening or port 25 in the partition Wall 24 between the centrifugal pump rotor chamber 16 and its intake or suction chamber 21. Thus, if when the pump is used as a bilge pump, there is water in the bilges of the boat, the bilge water will be pumped out of the bilges by the action of the centrifugal pump rotor 96 until the water level falls below the level of the pump intake, admitting air to the suction line and consequently admitting air to the intake chamber 21 so as to break the suction of the centrifugal pump chamber 16. When water again accumulates in the bilges, the centrifugal pump unit 11 will immediately pump it out through the volute passageway 17 and outlet or discharge port 19, due to the fact that the centrifugal pump chamber 16 is kept constantly primed by water entering its top or upper part through the priming passages 144 and 145 from the discharge chamber 136 of the resilient rotor pump 12. The main portion of the discharge of the latter is conducted from the discharge port 143 to a place of utilization, such as to the tail pipe or exhaust of the marine engine to which it is connected when used in a marine installation.

While the dual rotor pump 10 is operating, especially when it is used as a marine pump or as a building or excavation contractors pump, it occasionally draws in sand, dirt or other foreign matter. Since the pump shaft bearing is located in the intake chamber 21 of the centrifugal pump unit 11, however, the action of the centrifugal pump rotor 96 tends to keep such sand or foreign matter from entering the bearing bore 31 due to the suction created, greatly reducing wear lin the bearing 30 in comparison with conventional centrifugal pumps` where the shaft bearing is on the pressure side of the pump so that grit is forced into its bearing bore.

Meanwhile, any water or other liquid reaching the sealing device chamber 32 is prevented from proceeding further on by means of the sealing device 56 and gasket 54. The rubber ring 67 also assists in protecting the anti-friction bearing unit 43 by deecting moisture therefrom.

The word impeller as used in the claims will be understood to refer to the pump rotor, either of the centrifugal pump 11 or the rotary pump 12. The term centrifugal pump as used herein has the same meaning as is customary among hydraulic engineers, namely a pump having a rotating impeller which receives the water at its center and throws it outward by centrifugal force into a spiral or volute casing. The term rotary pump as used herein refers to rotary pumps with rotating impellers which do not operate on the centrifugal force principle of centrifugal pumps, namely, positive displacement rotary pumps, and includes various types of impellers or rotors. The resilient rotor or impeller pump shown in the drawings is the preferred type as it provides a high working efficiency at great pressures with the practical advantages set forth above. Positivedisplacement rotary pumps, however, include other types such as the intermeshing gear pumps, the eccentric rotor or impeller pumps having packing blades reciprocating radially with the impeller, the so-called Roots rotary pumps with interengaging lobed impellers, and the various radially reciprocating piston pumps having a cylinder barrel with radial pistons reciprocating therein, as in the so-called Hele- Shaw and Thoma pumps. Such distinctions between centrifugal pumps and positive displacement rotary pumps are set forth in standard tests such as, for example, Mechanical Engineers Handbook, edited by Lionel S. Marks, published by McGraw-Hill Book Co.

What .l claim is:

l. A dual impeller pump comprising a housing structure including a centrifugal pump housing having a centrifugal impeller chamber therein and a positive displaceent rotary pump housing having a rotary impeller chamber therein, a centrifugal pump impeller rotatably mounted in said centrifugal impeller chamber, and a positive displacement rotary pump impeller rotatably mounted in said rotary impeller chamber, said positive displacement rotary pump impeller having resilient vanes of elastic deformable material yieldingly engaging said positive displacement rotary pump housing, each of said housings having liquid inlet and outlet passageways communicating with their respective impeller chambers, said housing structure having a priming passageway therein leading from the outlet passageway of said rotary pump to the impeller chamber of said centrifugal pump whereby to supply priming liquid from said rotary pump to said centrifugal pump.

2. A dual impeller pump comprising a housing structure including a centrifugal pump housing having a centrifugal impeller chamber therein and a positive displacement rotary pump housing having a rotary impeller chamber therein, a centrifugal pump impeller rotatably mounted in said centrifugal impeller chamber, and a positive displacement rotary pump impeller rotatably mounted in said rotary impeller chamber, said rotary pump impeller having resilient vanes of elastic deformable material yieldingly engaging said rotary pump housing, each of said housings having liquid inlet and outlet passageways communicating with their respective impeller chambers, said housing structure having a priming passageway near the top therein leading from the outlet passageway of said rotary pump to the impeller chamber of said centrifugal pump near the top thereof whereby to supply priming liquid from said rotary pump to said centrifugal pump.

3. A dual impeller pump comprising a housing structure including a centrifugal pump housing having a centrifugal impeller chamber therein and a positive displacement rotary pump housing having a rotary impeller chamber therein, a centrifugal pump impeller rotatably mounted in said centrifugal impeller chamber, a positive displacement rotary pump impeller rotatably mounted in said centrifugal impeller chamber, said positive displacement rotary pump impeller having resilient vanes of elastic deformable material yieldingly engaging said positive displacement rotary pump housing, each of said housings having liquid inlet and outlet passageways communicating with their respective impeller chambers, said housings being disposed adjacent one another with a common wall therebetween, and a shaft rotatably mounted in said housing structure and extending through said common wall into both of said chambers, said shaft being drivingly connected to said impellers, said housing structure having a priming passageway therein leading from the outlet passageway of said rotary pump through said common wall to the impeller chamber of said centrifugal pump whereby to supply priming liquid from said rotary pump to said centrifugal pump,

4. A dual impeller pump comprising a housing structure including a centrifugal pump housing having a centrifugal impeller chamber therein and a positive displacement rotary pump housing disposed adjacent said centrifugal pump housing and having a positive displacement rotary impeller chamber therein, a centrifugal pump impeller rotatably mounted in said centrifugal impeller chamber, and a positive displacement rotary pump impeller rotatably mounted Vin said rotary impeller chamber, said positive displacement rotary pump impeller having resilient varies of elastic deformable material yieldingly engaging said positive displacement rotary pump housing, each of said housings having liquid inlet and outlet passageways communicating with their respective impeller chambers, said housings having a common wall therebetween, said housing structure having a priming passageway therein leading from the outlet passageway of said rotary pump through said common wall to the 'impeller chamber of said centrifugal pump whereby to supply priming liquid from said rotary pump to said centrifugal pump.

References Cited in the tile of this patent UNiTED STATES PATENTS 2,175,997 Saxe Oct. 10, 1939 2,439,315 Newton Apr. 6, 1948 2,461,865 Adams Feb. 15, 1949 2,512,764 Byram June 27, 1950 2,573,819 Weyer Nov. 6, 1951 2,603,160 LaBour July 15, 1952 2,612,844 Grise Oct. 7, 1952 2,671,406 Waller Mar. 9, 1954 2,687,096 Armacost Aug. 24, 1954 

